Chevrolet 1973 Overhaul Manual page 137

5 -3 4 BRAKES
1. End Cap
2. Gasket
3. Hydraulic Cylinder Housing
4. Cup
5. Valve Piston
6. Washer
7. Diaphragm
8. Washer
Fig. 5E--Removal and Disassem bly of C ontrol Valve
6. Using 1-3/8" wrench, remove end cap (1) and
gasket (2).
Cleaning
Use denatured alcohol to clean all metal, plastic and
rubber parts of the power cylinder. Immerse parts in
cleaning fluid and use a hair brush to remove foreign
matter. Blow out all passages, orifices and valve holes.
AIR DRY and place cleaned parts on clean paper or
lint-free cloth. If slight rust is found on inside surface of
power cylinder housing, polish clean with crocus cloth or
fine emery cloth, then follow with a thorough cleaning as
outlined above.
Use o f gasoline, kerosene, anti­
CAUTION:
freeze alcohol or any other cleaner with even a
trace o f mineral oil, will damage rubber parts.
Inspection
Wipe cleaning fluid from all parts and carefully inspect
each part for damage and wear. Inspect rubber parts for
cuts, nicks and distortion. These rubber parts are the key
to control of air flow and should account for the majority
of troubles traceable to leakage. If there is any question
whatever as to serviceability of any part, replace it.
Refer to "Inspection Chart" for more detailed
instructions.
Assembly (Fig. 4E)
Be sure to keep parts clean until
CAUTION:
reassembly. Re-wash at reassembly if there is
9. Valve Body Spring
10. Vacuum Poppet and Stem
1 1. Poppet Spring
12. Control Valve Body
13. Capscrews
14. Poppet
15. Retainer
16. Valve Body Cover
any occasion to doubt cleanliness - such as
parts dropped or left exposed for eight hours or
longer.
I f there is any suspicion o f contamination or
any evidence o f corrosion, completely flush the
car hydraulic brake system in accordance with
the Chassis Service Manual.
Lubricate rubber, plastic and metal friction
points with Delco Silicone Lube #5459912 (or
equivalent).
Piston and Push Rod
1. To install a new push rod seal (13) in push rod (8),
place new seal (rubber side down) on a clean block
of wood.
2. Hold push rod vertically (threaded end up) with
drilled end of rod resting on shaft end of seal and
then strike threaded end of push rod with soft
hammer to seat seal with its shoulder firmly against
end of push rod.
3. Dip cup (9) in clean brake fluid and assemble cup
on piston (10) with lip of cup as shown.
4. Install piston parts (2 through 12) on push rod from
seal end of push rod in order shown.
5. Slide snap ring (7), stop washer (6), bearing (4) with
"O" ring (5) installed in bearing groove, push rod
seal cup (3), seal retainer (2), retainer ring (12) and
piston assembly (1) on push rod.
6. Assemble retainer pin (11) through holes in piston
and rod. Secure pin in place with retainer ring (12),
making certain ring is seated in groove on piston.
Front Shell Assembly to Cylinder (Fig. 3E)
1. Place new gasket (3) in groove on flange of
hydraulic cylinder (1).
2. Assemble front shell (4) to cylinder, aligning cutout
in shell with porting in cylinder flange.
3. Assemble capscrew and tighten to 130-230 in. lbs.
4. If diaphragm, plate and return spring were
disassembled, install nut (7) and tighten to 160-200
in. lbs., (if nut is undercut, install undercut side
first) then washer (9), diaphragm plate (10), concave
side first, on threaded end of push rod.
5. Install diaphragm (11), washer (12) and nut (13) on
push rod, as shown, and securely tighten nuts (7
and 13) to 160-200 in. lbs.
6. Coat hydraulic cylinder bore with clean brake fluid.
Dip hydraulic piston and bearing parts in clean
brake fluid. Slide diaphragm return spring (8) onto
push rod, over hydraulic piston end (large diameter
of spring first).
7. Seat spring against concave surface of diaphragm
plate (10) and align entire assembly with hydraulic
cylinder bore.
OVERHAUL MANUAL